Biobased copolyesters from renewable resources: synthesis and crystallization behavior of poly(decamethylene sebacate-co-isosorbide sebacate)

Abstract

A series of long chain aliphatic copolyesters poly(decamethylene sebacate-co-isosorbide sebacate) (P(DS-co-IS)) were synthesized from commercially available biobased sebacic acid (SA), 1,10-decanediol (DD) and isosorbide (ISB) through a two-step melt polycondensation method. The molecular weight, composition, and microstructure of the P(DS-co-IS) copolyesters were characterized by GPC, ¹H-NMR, and ¹³C-NMR. The crystallization properties of the P(DS-co-IS) copolyesters were depressed, while the glass transition temperature was enhanced by the incorporation of isosorbide with a bulky rigid structure. The nonisothermal melt crystallization peak temperature and melting point decreased for P(DS-co-IS) with increasing the number of ISB unit; moreover, the equilibrium melting point temperature of P(DS-co-IS) was also reduced. However, the introduction of the ISB segment did not change the crystal structure of P(DS-co-IS), but it gradually decreases the crystallinity. Isothermal crystallization kinetics of neat PDS and its copolyesters indicated that PDS possesses high crystallization ability, which is a characteristic of long chain aliphatic polyesters. The crystallization mechanism remains unchanged for both neat PDS and P(DS-co-IS); however, the crystallization rates of P(DS-co-IS) decreased with increasing ISB composition and crystallization temperature. No evidence of ring-banded spherulites could be detected for this long chain PDS and its copolyesters in a wide temperature range even when supercooled.